Safety Evaluation of Red-Light Cameras

This is a final report on a study to evaluate the effectiveness of red-light-camera (RLC) systems in reducing crashes. The intended audience is professionals who make decisions about safety programs for intersections. The study involved empirical Bayes before-and-after research using data from seven jurisdictions across the United States to estimate the crash and associated economic effects of RLC systems. The study included 132 treatment sites and specially derived rear end and right-angle unit crash costs for various severity levels. Crash effects detected were consistent in direction with those found in many previous studies: decreased right-angle crashes and increased rear end crashes. The economic analysis examined the extent to which the increase in rear end crashes negates the benefits for decreased right-angle crashes. There was indeed a modest aggregate crash cost benefit of RLC systems even when accounting for the negative impact of rear end collisions. The benefit of RLC systems could increase further, if measures were taken to educate or alert drivers that vehicles preceding them could be stopping suddenly for a red light and thus reduce the likelihood of a rear end crash. A disaggregate analysis found that the greatest economic benefits are associated with the highest total entering average annual daily traffic, the largest ratios of right-angle to rear end crashes, and with the presence of protected left-turn phases. There were weak indications of a spillover effect that point to a possible need for a more definitive, perhaps prospective, study of this issue.

Michael F. Trentacoste, Director
Offices of Safety Research and Development

Notice

This document is disseminated under the sponsorship of the
U.S. Department of Transportation in the interest of information exchange. The
U.S. Government assumes no liability for the use of the information contained in this document.

The
U.S. Government does not endorse products or manufacturers. Trademarks or manufacturers' names appear in this report only because they are considered essential to the objective of the document.

Quality Assurance Statement

The Federal Highway Administration (FHWA) provides high-quality information to serve Government, industry, and the public in a manner that promotes public understanding. Standards and policies are used to ensure and maximize the quality, objectivity, utility, and integrity of its information. FHWA periodically reviews quality issues and adjusts its programs and processes to ensure continuous quality improvement.

ITS Joint Program Office and Office of Safety Research and Development
Federal Highway Administration
6300 Georgetown Pike
McLean, VA 22101

14. Sponsoring Agency Code

15. Supplementary Notes

Contracting Officer's Technical Representative:

Michael Griffith, FHWA Office of Safety Research and Development

16. Abstract

The objective of this final study was to determine the effectiveness of red-light-camera (RLC) systems in reducing crashes. The study used empirical Bayes before-and-after research using data from seven jurisdictions across the United States at 132 treatment sites. The purpose of the study was to estimate the crash and associated economic effects of RLC systems and specially derived rear end and right-angle unit crash costs for various severity levels. Crash effects detected were consistent in direction with those found in many previous studies: decreased right-angle crashes and increased rear end ones. The economic analysis examined the extent to which the increase in rear end crashes negates the benefits for right-angle crashes. The analysis showed an aggregate crash cost benefit of RLC systems. A disaggregate analysis found that the greatest economic benefits are associated with the highest total entering average annual daily traffic, the largest ratios of right-angle to rear end crashes, and with the presence of protected left turn phases. There were weak indications of a spillover effect that points to a need for a more definitive, perhaps prospective, study of this issue.